The present invention relates to an apparatus for measuring a pulse compression ratio, and more particularly to an apparatus which receives a high frequency pulse signal emitted from a pulse compression radar using a two-phase coded modulation system, in order to measure the pulse compression ratio.
In recent years, a pulse compression radar having excellent characteristics in distance resolution and sensitivity tends to be widely used. In a military radar warning system or the like, for example, it is required to receive pulse compression radar signals emitted by a plurality of enemy radars, classify each radar signal as to its emitting source, and assume the sort of each emitting source, e.g. the use for the radar.
In a conventional measurement system for this purpose, though factors such as a carrier frequency, a pulse width, etc. of the received radar signal are utilized, these are insufficient for the pulse compression radar, so it is necessary to measure an individual pulse compression ratio of the puluse compression radar and utilize it. However, an apparatus for measuring a pulse compression ratio, which can be used fo classifying the pulse compression radars and assuming the purpose of their use, has not hitherto been provided.
The followings are requirements for the military radar warning apparatus with regard to the pulse compression radar.
First, in the military radar warning system, as it is usual that pulses transmitted from a plurality of radars are received, so pulse train interleaved by pulses from different radar transmitters tend to be received. Therefore, in order to classify each pulse constituting the pulse train as to each transmitter, it is necessary to measure the pulse compression ratio of every one pulse.
Further, in the interleaved pulse train there is quite a possibility that the subsequent pulse may reach immediately after one pulse reached, and hence it is required to complete the measurement of pulse compression ratio for one pulse within its pulse width, and to make ready for measuring pulse compression ratio of the subsequent pulse.
In addition, in case of the military radar warning system installed in a small aircraft such as a fighter, it is strongly desired that the measurement apparatus should be small in size and light in weight.